LI Shirong1, LI Dongmei2, FAN Xiaoyu1, HOU Shi1, HU Daodao1*
(1 School of Materials Science and Engineering, Shaanxi Normal University,Xi′an 710119, Shaanxi, China;2 Army Academy of Border and Coastal Defence, Xi′an 710108, Shaanxi, China)
Abstract:
Lead white darkening is a common disease of paper-based relics, which makes the cultural heritages lost their original appearance. In this paper, the method, the lead dioxide (PbO2) composite as anode and the conductive hydrogel as cathode used to restore lead white darkening PbS into the original lead white, was investigated. The results indicated that PbS could be transformed into PbSO4. Additionally, a possible mechanism on this process was proposed, and proved by using fluorescence spectroscopy and X-ray photoelectron spectroscopy (XPS). During the electrolysis, PbS is oxidized to PbSO4 by the hydroxyl radicals generated on the PbO2 anode, as a result, the darkened PbS becomes lead white. Compared with traditional method based on H2O2 oxidation, the new method possesses local controllability for treated area.
KeyWords:
paper cultural relics; lead white; lead white darkening; electrolysis
